1. Field of the Invention
The present invention relates to a novel fluid analysis element for analyzing the refractive indices, concentrations, and the like of fluid samples. The present invention also relates to a fluid analysis apparatus.
2. Description of the Related Art
Interference filters, such as etalon filters, are known as light modulating elements that absorb specific wavelengths of light and modulate the light. Conventional interference filters are difficult to manufacture, due to the high requirements regarding accuracy of smoothness and film thickness, and therefore are expensive. In addition, it is difficult to manufacture conventional interference filters having large areas, due to these reasons. Further, because the structures of the conventional interference filters are fixed, the light modulating properties thereof are also fixed. Accordingly, in the case that the wavelength of light to be absorbed (filtered) changes, a different interference filter needs to be provided, which precludes flexibility in design changes to optical systems.
In view of this, International Patent Publication No. WO2002/082042 discloses a light modulating element comprising an apertured member having fine apertures (nodes) with diameters of 1.0 to 1.6 μm, which are filled with fluids. This light modulating element is of a photonic crystal structure, in which the diameters of the fine apertures are greater than the wavelength of light. This light modulating element modulates light with the interference effects of photonic crystals.
Japanese Unexamined Patent Publication No. 2001-174719 discloses a light modulating element comprising a container, in which a pair of light transmissive wall members is provided. The wall members are separated in the direction of an optical axis, and the distance therebetween is adjustable. Fluid fills the space between the walls within the container. In this light modulating device, multiple reflection (resonance) occurs between the pair of transmissive wall members, to cause multiple beam interference. Thereby, light of specific wavelengths is absorbed, and the light is modulated.
The light modulating elements disclosed in International Patent Publication No. WO2002/082042 and Japanese Unexamined Patent Publication No. 2001-174719 both are capable of changing the light modulating properties by changing the fluid therein. However, it is difficult to perform fine high resolution light modulation as is possible with etalon filters.